Though siblings can sometimes be a pain, having a sister might be good for kids' emotional health, according to a new study.

The results show young adolescents who had sisters either younger or older were less likely to experience negative feelings, such as loneliness and guilt.

"Even after you account for parents' influence, siblings do matter in unique ways," said study researcher Laura Padilla-Walker, of Brigham Young University in Utah. "They give kids something that parents don't."

The study is part of BYU's Flourishing Families Project and included 395 families with more than one child, at least one of whom was an adolescent between the ages of 10 and 14. The researchers gathered a wealth of information about each family's dynamic at the study's start and then followed up one year later.

Sisters seemed to help siblings avoid negative emotions. Those adolescents with sisters were less likely than those without sisters to indicate feeling lonely, unloved, guilty, self-conscious and fearful. It didn't matter whether the sister was younger or older, or how far apart the siblings were age-wise.

Brothers matter as well, though their positive influence manifests in different ways. Having a loving sibling of either gender promoted good deeds, such as helping a neighbor or watching out for other kids at school. In fact, loving siblings fostered charitable attitudes more than loving parents did. The relationship between sibling affection and good deeds was twice as strong as that between parenting and good deeds.

"For parents of younger kids, the message is to encourage sibling affection," Padilla-Walker said. "Once they get to adolescence, it's going to be a big protective factor."

Many parents worry about the seemingly endless fighting between siblings. Indeed, the study found hostility was associated with greater risk of delinquency. But Padilla-Walker also sees a silver lining in the data: The fights give children a chance to learn how to make up and to regain control of their emotions skills that come in handy later in life.

"An absence of affection seems to be a bigger problem than high levels of conflict," Padilla-Walker said.

The study is published in the August issue of the Journal of Family Psychology.